We are at war with synthetic food dyes. Scientists are racing to reinvent the culinary color wheel.
Illustration by Nicholas Konrad
During Biden’s final week in office, the Food and Drug Administration announced that Red No. 3, a synthetic dye that Americans have consumed for nearly a century, would be banned starting in 2027. It cited studies showing that large quantities of the coloring caused cancer in rats. (According to a 1960 law, no food additive that’s carcinogenic in animals can be authorized by the F.D.A.) Three months later, Robert F. Kennedy, Jr., Trump’s Secretary of Health and Human Services, went further, calling synthetic dyes “poisonous compounds” that “offer no nutritional benefit and pose real, measurable dangers to our children’s health and development.” He said at a press conference that he’d reached an “understanding” with manufacturers: artificial food colorings would be phased out as early as next year. Our food may soon look very different than it does now.
In the U.S., nine synthetic dyes currently color products as diverse as candy, hot dogs, canned fruit, breakfast cereal, and even salad dressing. The evidence that they make us sick is limited, but in the early two-thousands a study published in The Lancet found a relationship between artificial colorings and hyperactivity in roughly two hundred and fifty children in England, prompting the addition of warning labels on colorants in the European Union. A 2021 report by California health officials said that synthetic dyes were associated with “adverse neurobehavioral outcomes in children,” and that some children are more sensitive than others. Many states are pursuing bans. So far, the Trump Administration has not finalized any new prohibitions or announced any official agreements from manufacturers, but officials seem confident that companies will comply. “For companies that are currently using petroleum-based red dye, try watermelon juice or beet juice,” Martin Makary, the commissioner of the F.D.A., said at the press conference, to laughter and applause from the audience. “For companies currently combining petroleum-based yellow chemical and red dyes together, try carrot juice.”
To compensate for the disappearance of synthetics, the F.D.A. recently authorized four new color additives: a white powder made from calcium phosphate, and three sources of blue, made from algae, butterfly-pea flowers, and gardenia fruit. Such dyes can create brilliant hues in some foods—but they tend to be fragile and unstable in others. Spirulina, a powdered algae, often clumps, settles at the bottom of liquids, and tastes faintly of ocean brine. Butterfly pea is one of many blue dyes with an acid problem: it makes a dazzling blue at a pH of around 6, roughly the acidity of milk, but add more acid and it turns violet, then pink. (In alkaline liquids, it turns green.) Linsey Herman, a vice-president of research and development at Nature’s Path, which sells organic foods and doesn’t use synthetic dyes, told me that a company she used to work for tried to make all-natural tie-dye cookies; colorants such as vegetable juice and flower extract couldn’t withstand the baking process. More recently, beet powder that coated one of Nature’s Path’s cereals went in looking bright red and came out a dull brown. Without artificial coloring, one outcome is certain. “Things will definitely not be as vivid,” Herman told me. “It’s very hard to achieve the same kinds of reds, and the same kind of blues and greens.”
On a humid and overcast afternoon in June, I travelled to Ohio State University, in Columbus, to visit the laboratory of Monica Giusti, a food scientist who works to find natural alternatives for artificial colorings. Her nails were painted bright blue and seemed to pop with color when she tucked her silver hair behind her ears. In today’s supermarkets, Giusti said, a small number of acidic foods and drinks are blue—but mostly with the help of Blue No. 1 and Blue No. 2, which are in R.F.K., Jr.,’s crosshairs. Yet on the table in front of us were three vials of blue liquid with a pH of 4—roughly the acidity of coffee or orange juice. All of them contained natural dyes that the lab had developed.
A Ph.D. candidate in Giusti’s lab, Xinyue Fan, has started testing these dyes in various foods. She added them to carbonated water, which changed from clear to sky-colored. But there was something elusive about them; when she added them to lemon-lime soda, they didn’t take, and she isn’t yet sure why.
I asked her what would happen if more acid were added to the test tubes. Using a dropper, Giusti added the equivalent of a splash of vinegar or lime juice, and the blue intensified. At around pH 2.9—the acidity of Dr. Pepper—it started to look more like a dark purple. Only at a pH of 2—a level of acidity we rarely encounter, except in very sour candy—did the liquid start to look reddish pink. The blue, which had been so vibrant a few seconds earlier, disappeared.
Giusti grew up in Peru, and as a graduate student she studied under Ron Wrolstad, a fruit-and-vegetable expert at Oregon State University. She became a specialist in a group of molecules called anthocyanins, which color red roses, blue cornflowers, and common violets, in addition to such foods as black currants, blueberries, red cabbage, and purple potatoes. In Wrolstad’s lab, Giusti tried to develop a colorant for maraschino cherries, which are a tricky food: they’re processed in bisulfite, which not only bleaches out the cherry’s color but also lingers in small amounts, potentially degrading whatever natural colorant is added later. To top it all off, they are stored at room temperature in clear glass jars. Giusti managed to extract a suitable red colorant from seventy pounds of hand-peeled radishes. She remains sensitive to the smell of radishes to this day.
Much of Giusti’s work for the food industry is confidential, but she is known to be part of a team working with Mars Inc. that spent years developing an alternative blue for M&M’s. (It, too, was unstable in acid.) To collect pigments, she could in theory determine their chemical structures and then make or order them in synthetic form. Technically, natural dyes can be synthetically produced, as long as they are “nature-identical.” But that process is expensive, so she and her students juice eggplants, mash berries, and steep vegetable skins in search of robust and vivid colors. In her lab, I watched a student dry a light-purple berry juice into a powder. Another was trying to reproduce the anthocyanin found in red wine. His aim was to replicate not the hue but the relative durability of its color. “Some people think maybe we could just remove the colors from food,” Giusti told me, shaking her head. “It would completely change your experience.”
People have been coloring their food since at least the time of ancient Rome and Egypt, often for ritualistic or religious purposes. According to Charles Spence, an experimental psychologist at Oxford University, natural dyes—yellow from saffron and egg yolks, green from crushed plants, red from sandalwood—became especially popular in the Middle Ages. Blood could be used to make brown and black. A fourteenth-century cookbook reported that a lichen called orchil could make reds or blues, depending on how tart the food was.
The first synthetic dye was a shade of mauve, invented in the mid-nineteenth century from by-products of coal processing. After the rise of mass production, companies used food dyes to make their products stand out, and also for the opposite reason: to make foods look more like themselves. Margarine was dyed yellow to make it look more butter-like; hot dogs got a pink tint so that they wouldn’t appear gray. Today’s synthetic dyes are made from hydrocarbons in purified petroleum, which have unusually hardy chemical structures. A molecule with alternating double and single bonds, for example, tends to be more durable, and helps explain why a dye such as Blue No. 1 is stable in acid and heat.
Food dyes began to raise wider health concerns around 1950, when Orange No. 1 in Halloween candy gave trick-or-treating children diarrhea and rashes. The F.D.A. later found that it damaged the organs of lab animals. Red No. 32 was associated with cancerous growths in animal trials. By 1956, the FDA had banned both dyes. The case against today’s dyes is not as black-and-white. Some consumer groups argue that, because synthetic dyes have no nutritional value, they should be outlawed even if their health effects are unclear. Some health experts deem them harmful because they make unhealthy and ultra-processed foods more attractive.
Giusti and Fan’s search for a stable blue looked to a flower for inspiration: the hydrangea. When Fan was growing up in Beijing, she wondered why these plants blossomed with both blue and pink flowers. A hydrangea’s hue comes from an anthocyanin—but, unusually, its petals become more blue as the soil becomes more acidic. In 2019, scientists at Nagoya University, in Japan, helped explain why: the anthocyanin combined with a co-pigment found in the plant, and with aluminum released from acidic soils. The researchers named this combination the “hydrangea blue-complex.”
Getting the blue complex directly from the hydrangea is not practical for food, Fan explained. It’s difficult to extract intact from the flower, and hydrangeas are not considered edible in large volumes. Instead, Giusti and Fan looked for nontoxic candidates among roughly seven hundred anthocyanins.
Fan, who was wearing a white lab coat and blue gloves, showed me several vials of purple and blue liquid that she’d left out since February, at room temperature, to see how long the colorants would last. They were as bright as when she’d first made them. I saw a blue that wasn’t quite as neon as teal Trix cereal, or as opaque as blue Skittles, yet it seemed richer than, say, blue Gatorade. I could easily imagine it tinting a Jolly Rancher or a gummy worm.
A curious kind of alchemy was required to mix these colors. Fan showed me three vials that each contained a reddish liquid, and a fourth whose contents were straw-colored. The red vials contained the results of their search—juices from two fruits and a vegetable whose anthocyanin structures were akin to the hydrangea’s. The yellow test tube was filled with a steeped “tea” containing the co-pigment from hydrangeas, plus some aluminum, to emulate what the plant pulls from the soil. Mixed together, they mimicked the trinity in the hydrangea blue-complex.
When Fan used a dropper to add one of the red liquids to a clear acidic solution, the color unfurled like a ribbon, fading into pink as it dispersed. Next, she added the yellow liquid. I expected the red and yellow to mix into orange, as they would on a palette of paint. Instead, as the yellow hit the pink, it gradually turned a dark violet blue—the exact color of deep-blue hydrangeas.
Before I met Giusti, I thought I knew what a color was: a particular wavelength of light that enters the eye and is interpreted by the brain. This isn’t incorrect, but it’s incomplete. During my visit, Giusti and I walked around the horticultural garden on campus, admiring the colors of flowers. She noted that most colorful objects are defined by the wavelengths that they reflect; a sunflower is not yellow because it “is” or “contains” yellow, but, rather, because it absorbs every color except yellow. Most plants are green because chlorophyll, which produces energy from sunlight, absorbs every wavelength except green. This is also a reason that blue is rare in nature. Blue and violet waves are high in energy, and plants have evolved to absorb them.
Sometimes, there’s even more to color than that. Bluebirds look blue, for example, not because they contain blue-reflecting pigments, but because of an optical illusion: light scatters off prismatic nanostructures in their feathers. We see the sky, and many butterflies, as blue for similar reasons. “They are blue, but they do not have a blue pigment,” Giusti said. “We say that color doesn’t belong to the object, color belongs to the experience.” When I saw anthocyanins change hue in the laboratory, they were experiencing a change in structure, which affected the wavelengths that bounced off them; I was experiencing a change in the color I perceived.
When consumers experience new colors in foods that they know and like, they sometimes react with revulsion. In 2017, General Mills tried to remove artificial colorings from Trix and transition to using natural dyes. They tested sixty-nine colorants before releasing a new version of Trix with soft, autumnal colors drawn from turmeric, annatto, radishes, and purple carrots. (Blue and green Trix were omitted from the mix.) Soon, sales dropped, and customers called the muted colors “disgusting.” In the end, General Mills reverted to synthetics. A line of Kraft Jell-O and pudding without artificial colorings was also unsuccessful.
Still, our tastes for differently colored foods can evolve—just as they did when synthetic dyes originally became widespread. Experts once predicted that people would never want blue food or drinks. “We have a deep-seated dislike of blue foods,” Lyall Watson, a botanist and an anthropologist, wrote in the nineteen-seventies. “Take a trip through a supermarket and see how many blue ones you can find.” Yet after red synthetic dyes attracted scrutiny in the twentieth century, food companies successfully introduced a new artificial flavor and color: blue raspberry. It remains popular in ice desserts and candies to this day. “Once a color obtains some kind of cultural meaning, people can take advantage of or appropriate the meaning,” Ai Hisano, a cultural historian at the University of Tokyo, told me. She pointed out that, during a mass movement to eliminate synthetic dyes, “duller or earthier colors might become preferable.”
Not long ago, I walked down the breakfast aisle of my local grocery store, looking for a box of cereal. Hisano had a point: numerous brands used muted colors and advertised themselves as organic or all natural. Nature’s Path sells turmeric-tinted flakes (“Makes Golden Milk!”) and strawberry-and-chocolate Turtle Splash cereal, which features light-pink and umber turtle shapes. And yet the company’s best-selling products all seem to be beige or brown: old-fashioned oatmeal, cornflakes, bran.
Nearby were brightly colored Froot Loops, Fruity Pebbles, and Lucky Charms. As I scanned the shelves, I thought of a nineteen-fifties advertisement for Trix: “Pour a rainbow for breakfast tomorrow.” I wondered whether a hydrangea-blue cereal, made from a natural anthocyanin dye, would be as eye-catching as these artificially colored ones. Among the all-natural brands, the color might seem anathema, even unappetizing. In the end, feeling overwhelmed by all the choices, I picked out a simple bag of plain granola. I could always add a handful of blueberries, for color.